I. Introduction Descriptions of the macroscopic findings in the lungs of individuals with fatal asthma date back as far as the seventeenth century. In 1883 spirals of mucus occluding airways in such cases were described by Curschmann (1). In their comprehensive review of asthma pathological characteristics and mechanisms, Huber and Koessler (2) in 1922 identified 15 cases in which the microscopic findings in fatal asthma had been described and added 5 cases of their own. In the frrst quantitative study of asthma pathological features, they compared these cases to a nonasthmatic group using a stratified technique of sampling large and small airways and even considered the confounding effects of muscle spasm on measured airway dimensions. They documented the classic pathological findings in fatal asthma, including overinflated lungs, mucus plugs occluding airway lumens and containing shed epithelial cells and Charcot-Leyden crystals, variable epithelial damage, dilated mucus gland ducts, thickening of the "basement membrane," infiltration of round cells and eosinophils into the airway wall, and
2 James and Carroll
The precise definition of subdivisions of the bronchial wall is confounded by the lack of uniformity among groups of anatomists, pathologists, and physiologists (14). For the purposes of this review the airway will be partitioned as follows: the lumen, which includes the mucus layer; the epithelium (or mucosa); the submucosa, which includes all structures bound by the subepithelial basement membrane and the smooth muscle; and the adventitia, which includes structures between the smooth muscle and the outer limit of the loose connective tissue surrounding the airway.